The present invention relates to a support for transfer images or slide-off images, e.g., decals, composed of absorbent paper, one side of which supports an applied barrier layer and a water-soluble separation layer for receiving a detachable image layer in the form of a print and/or lacquer layer.
Supports for transfer images or slide-off images are known, for example, from German Offenlegungsschrift No. 25 51 860, corresponding to U.S. Pat. No. 4,049,860, or from U.S. Pat. No. 2,970,076. They disclose a water-soluble or heat-soluble separation layer, to which the decorative image is printed by means of screen printing or offset printing. During the transfer of the decorative image to the intended carrier, which can be performed manually or mechanically, a residual amount of the separation layer constituents is simultaneously transferred in all process methods. In general, the separation layer is composed of gum arabic, polyvinyl alcohol, carboxymethyl cellulose, polyvinyl acetate, polyglycols or oligosaccharides or polysaccharides.
It is an important characteristic of these co-transferred separation layer constituents that they burn without leaving any residue during the subsequent burning-in of the decorative image which in most cases is composed of mixtures of inorganic pigments and a lacquer mask.
If the carriers are glass or ceramic objects with an underglaze and the process is carried out in a conventional manner in the presence of water-soluble separation layer constituents and at high burning-in temperatures, decorative final products which are absolutely free of tint, are obtained.
The co-transfer of large amounts of water-soluble separation layer constituents is disadvantageous, above all in cases where they are transferred to unglazed ceramic objects or where critical burning-in methods, such as fast burning-in, or lower burning-in temperatures are used. In these cases, permanently visible, undesired remnants of the separation layer constituents are left after the burning-in.
Transfer images or slide-off images which are not used in the ceramic field are also known. After having been transferred to glass, metal, enamel, plastic, etc., these images are fixed at temperatures of up to 250.degree. C., whereby the lacquer mask surrounding the decorative image is maintained. It is a substantial disadvantage of the known separation layers that co-transferred separation layer constituents dissolve due to the attack of water on the carrier and reduce or neutralize the adhesion of the decorative image. It is, of course, also possible to produce images of this kind by means of reverse side printing, which presents the advantage that a heat-activatable adhesive is applied during the last working step. After the heat treatment these images permanently adhere to the carrier. It is, however, a disadvantage that after the transfer the image can no longer be positioned manually, since no water-soluble, slidable separation layer is present between the decorative image and the carrier. In cases where the carrier is irregularly shaped, this disadvantage is particularly serious.